Q: My questions have to do with existing ungrounded circuits in older homes. My understanding is that you should always replace worn-out two-slot receptacles with new two-slot receptacles (although they’re not always easy to find). However, I’ve also been told that in some locales you can install a three-prong receptacle in an ungrounded circuit as long as you fill the ground slot with epoxy. This is presumably to prevent someone from using a grounded appliance on the ungrounded circuit. What’s the code requirement, and what about this epoxy business?